The 50-year-old had drunk seven pints of lager before the Friday night fixture on August 4, 2017, and said he used violence against Mr O'Donnell because he was saying "West Ham" at him - the two clubs have a fierce rivalry.

Leicester Crown Court heard how the victim suffered a skull fracture and bleeding on the brain as a result of the "entirely unnecessary as well as aggressive blow".

Mr O'Donnell was found in a critical condition two weeks later at his house in Newark, Nottinghamshire, after falling down the stairs, and was pronounced dead in hospital on August 24.

As a result, she said no evidence would be offered on the manslaughter charge and Judge Gregory Dickinson QC said he would be directing a not guilty verdict.

Millwall supporter Andrew Lewis jailed

Ms Moore said Mr O'Donnell suffered from memory loss and severe headaches when he was released from hospital after the initial attack.

Lewis, of Bromley, South London, was jailed on Wednesday after admitting one count of causing grievous bodily harm at a previous hearing.

The judge told Lewis: "This was an entirely unnecessary as well as aggressive blow to a man who, at that moment, was incapable of defending himself because he was looking away.

"You know that serious injury can be caused by serious violence because you have a previous conviction for causing grievous bodily harm.

"It could easily have been worse. Everyone should be safe to attend matches like this without having to experience or witness violence."

The court was told Lewis had another previous conviction in 2004 for assaulting a taxi driver in Cardiff - the same weekend as Millwall played Manchester United in the FA Cup final at the city's Millennium Stadium.

The City Ground

Defence QC Matthew Sherratt said: "He has let himself down, he has let his family down and he has let his son down.

"He should never have punched Mr O'Donnell and he is sorry."

The match was won by the hosts 1-0 and had been brought forward by a day to avoid clashing with cricket at neighbouring Trent Bridge.